Motor starter



F. H. WINTER- MOTOR STARTER Nov. 26, 1940.

Filed Dec. 14, 1939 Inventor:

Fred H. WI nter, 108 $0447 His Attorneg Patented Nov. 26, 1940 UNITED STATES PATENT OFFICE MOTOR STARTER New York Application December 14, 1939, Serial No. 309,219

6 plaims.

This invention relates to motor starters, more particularly to multi-point motor starters, and it has for an object the provision of a simple, reliable, improved, and inexpensive motor starter 8 of this character.

In carrying the invention into eilect in one form thereof, a current limiting device such as a resistor is connected in the armature circuit of the motor and switching means are provided 10 for sequentially rendering portions of this current limiting device ineffective. This switching device comprises a plurality of magnetic circuits which are spaced apart so as to be magnetically independent or! each other together with a single 15 operating coil interlinking all of these magnetic circuits. 'The magnetic circuits are separately adjustable to respond to diilerent values of magnetic flux for actuating contacts which control portions of the current limiting device. A suit- '0 able energy storage device is provided which discharges a decaying current through the coil thereby causing the independent magnetic circuits to respond sequentially to the different values of flux to which they are adjusted to render portions of the current limiting device ineilective. For a better and more complete understanding of the invention, reference should now be had to the following specification and to the accompanying drawing, in which Fig. 1 is a simple, diagrammatlcal sketch of an embodiment of the invention and Fig. 2 is a modification. I

Referring now to the drawing, the armature iii. of a motor i is arranged to be connected to a suitable supply source which is represented by 35 the conductors ii, l2. Motor I0 is provided with a separately excited field winding its which is arranged to be connected by means of switch it to supply source II, II. or to any, other suitable source oi excitation.

40 A suitable current limiting device such as a resistor i4 is connected in circuit with the armature iii. of motor Ill, and a suitable electromagnetic switching device I5 is provided for sequentially rendering portions la, its and lie of the 5 current limiting device ineiiective.

Switching device It comprises a plurality of separate magnetic circuits illustrated as the core structures l6, l1, and it of a plurality of'normally closed contactors. These core structures are sep- 0 arated from each other so that they are substantially magnetically independent of each other, i. e., so that the flux of one core structure does not pass into another core structure. For the purpose of reducing magnetic leakage between the 55 separate magnetic circuits to a minimum, spacers (not shown) made of a nonmagnetic material such as brass are placed between the core structures. The spacing of the core structures illustrated in the drawing is exaggerated for the purpose of clear illustration of the electrical circuits. 5 Core structures i6, i1, and II are respectively provided with armatures its, IL, and I81 and with normally closed contacts, l6, lit, and l8b, respectively, which are opened in response to attraction of the armatures. These contacts con- 10 trol the short circuiting and insertion in the armature circuit of portions "1, its, and le of current limiting device It. The core structures are provided with adjusting screws iiic, He. and He, respectively, for adjusting the pressure of the movable contacts against the stationary contacts. Adjustment of these adjusting screws naturally ailects the time of pick up and drop out of the armatures. If it is desired to have the same pressure on all contacts and also to cause the armatures to respond at different values of flux to provide sequential operation, additional means such as shims for varying the reluctances of the magnetic circuits are provided. Such shims may be secured to the faces of the armature opposite the core face at the movable end of the armature. Thus by means of the adjusting screws or by means of a combination of adjusting screws and shims, the value of flux at which,the annatures respond and the time of response can be varied as desired.

A single operating coil i9 is provided for exciting the separate core structures. As shown in the drawing, this coil links all of the core structures.

A suitable electrical energy storage device such as the condenser 20 is provided for discharging a decaying current through the coil It so that the armatures 6., i1, and I!- which are adjusted for response to different values of magnetic flux will operate in sequence.

For the purpose of initiating operation of the starter, a suitable control device illustrated as a manually actuated push button type switch 2i is provided. An electromagnetically actuated contactor 22 which is responsive to actuation of starting control device 2| is provided for connecting the armature of the motor to, its source of supply and for causing the condenser 20 to discharge through the operating coil i9.

With the foregoing understanding of the elements and their organization in the completed 7 a motor starter, the operation of the starter will description.

i3. are adjusted to drop out sequentially in the order enumerated in response to the decaying current discharged into the coil l9 by condenser 5 20. It is also assumed that the parts are in the normal deenergized position in which they are illustrated in the drawing.

The field of the motor I is energized by closing switch H to connect field winding "is to the supply source H, l2. The push button switch 2| is then depressed to close its contacts and connect operating coil H to the supply source H, i2. The circuit is traced from the side ll through stop" push button 23, contacts of start push button 2 I, conductor 24, normally closed contacts 22b of contactor 22, conductor 25, operating coil iii to the side I 2 of the supply source. Simultaneously, the push button 2| connects condenser 20 to the supply source through conductor 24, normally closed interlock cont-acts 26 of the starting device and conductor 21 to side l2 of the supply source. The resistor 23 which controls the rate of discharge of the condenser is short circuited by the interlock contacts 26, and consequently the condenser 20 is connected directly across the supply source and charges at a rapid rate.

In response to the energization of operating coil l9, armature's Ilia, 1a, and His pick up and separate their contacts I61), "b, and I81), thereby inserting portions I48, He, and I40 of resistor M in the armature circuit of motor iii. In picking up, armatures Ilia, I18, and I8 close normally open interlock contacts 299. and 29s to complete an, energizing circuit for the operating coil of contactor 22 from the start push button 2| to the side l2 of the supply source. Interlock contacts 26 are also separated to insert resistor 28 in circuit with condenser 20. The movable contact 40 member 290 of the interlock rests on push rods Ilia, lid, and lad which project from the movable contact members'which are attached to armatures I55, I11, and I83. Thus all oi the armatures must be picked up and contacts lib, lit, and lab 5 open with resistor sections He, He, and I40 inserted in the motor circuit before contactor 22 can be energized to close to connect the motor armature to the source.

Contactor 22 picks up in response to energiza- 50 tion and closes its normally open contacts 22a and 22c and opens its normally closed contacts 22b. Contacts 22 in closing complete the armature circuit of motor ill to the supply source with resistor portion-s Me, Me, and [4c included in circuit, As 55 a result motor In starts and accelerates. Contacts 22b in opening interrupt the connections of coil l9 and condenser 20 to the supply source.

Contacts 22a in closing complete a holding circuit for the coil of contactor 22 independent of 60 start push button 2| and the normally open interlocks 299., 29b of the switching device 15. The push button 2i may now be released.

As soon as the connections of coil I9 and condenser 20 to the supply source are interrupted, 65 the condenser begins to discharge through the coil l8. Initially the discharge current is high but it decays at a rate determined by the re-. sistance of the discharge resistor 28.

After a predetermined interval of time, the our- 70 rent will decay to the value at which armature i6 is adjusted to drop out. As a result contacts I61, close and short circuit portion ii. of the resistor l4, and the speed of the motor is increased to a raw value. After another predetermined interval 75 ct time the discharge current of the condenser 22 will decay to a lower value at which armature I1- is set to drop out. As a result contacts llb will close and short circuit portion I4t of resistor l4, and the speed of motor III will be further accelerated.

Finally aiter another predetermined interval of time, the condenser discharge current decays to the value at which armature I8. is set to drop out. Armature I82 in dropping out, closes contacts 18b to short circuit section I46 of the resistor. Motor I0 is accelerated to full speed. In the dropped out position 01 armature l8a, interlock contacts 28 are closed to short circuit resistor 28.

The motor continues to operate at full speed until the stop button 23 is depressed to deenergize the operating coil of contactor 22. As a result of deenergization, contactor 22 opens its normally open contacts 22c to disconnect motor I0 from the source, and also open its normally open contacts 223 and closes its normally closed contacts 22b to leave the device in a reset condition for the next starting operation.

In the modification of the invention illustrated in Fig. 2, the operating coil which links the magnetic structures of the contactors is divided into two portions comprising a portion having a large number of turns, and a portion 35. having a much smaller number of turns. In a typical example the portion 35 would have 25,000 turns of four mil wire with a total resistance-of approximately 17,000 ohms, and the portion 350 would have 2,000 of eight mil wire with a total resistance of 180 ohms. These two winding portions correspond to the operating coil IQ of Fig. 1.

The capacitor 36 which corresponds to the capacitor 20 of Fig. 1 is connected in parallel with only the high turn, high resistance portion 35 of the operating winding. No resistor corresponding to the resistor 28 is connected in series with the capacitor 36. An interlock 31 which corresponds to the interlock 26 of Fig. 1 is provided with normally closed contacts which normally short circuit the capacitor 36 and the high resistance portion 35 of the operating winding. The remainder of the modification of Fig. 2 is identical with the structure of Fig. 1.

The operation is as follows: Closing the start switch 38 connects the low turn portion 35. oi the operating coil across the source 39, 40. The circuit is traced from the side 39 of the source through stop switch 4|, start switch42 interlock 43 (corresponding to interlock 22b of Fig. l), normally closed interlock contacts 31, low turn portion 5a of coil to side of the source. In response to energization of portion 35. of the coil, the armatures of the magnetic structures corresponding to armatures I68, lb, and I81 0! Fig. 1 are picked up and resistor sections corresponding to lhsHb, and I 4a are inserted in the armature circuit of the motor. Thereafter, the interlock corresponding to interlock 29., 29b, 29 of Fig. 1

' is closed and as a rault the line switch corresponding to switch 22 of Fig. 1 is closed to connect the motor to the line.

The closing oi the armature corresponding to armature I8. 01 Fig. 1 opens interlock 31 to interrupt the short circuit oi capacitor 36 and of portion 35 of the operating coil. When the contacts 31 open, the capacitor 36 is'quickly charged. However, in filling the capacitor current flows for a small fraction of a second of suflicient amount, through the low turn portion 35; of the coil to insure that the armatures are completely closed against their cores.

spasms 3 The closing of the line switch corresponding to line switch 22 oi Fig. 1 opens contact 48 thereby disconnecting capacitor 30 and operating coil ll, 35. from the side I I oi' the supp y source. There- 5 upon the capacitor it begins to discharge through the high resistance portion 35 of the operating coil, and as the discharge current decays, the contactor armatures controlled by the coil dropout in sequence and effect the short circuiting oi the resistor sections in the motor armature circuit and the acceleration oi the motor in the manner described in the explanation oi the operation oi Fig. 1.

Although in accordance with the provisions oi the patent statutes this invention is described in concrete iorm and the principle thereof has been described together with the best mode in which it is now contemplated applying that principle, it will be. understood that the elements and connections illustrated are merely illustrative and that the invention is not limited thereo, since alterations and modifications will readily suggest themselves to persons skilled in the art without departing from the true spirit oi the invention or from the scope of the annexed claims.

What I claim as new and desire to secure by Letters Patent oi the United States, is:

1. A motor starter comprising in combination, a current limiting device connected in the armature circuit oi the motor, means for rendering portions oi said current limiting device ineiiective comprising an electromagnetic switching means having a plurality 01' independent magnetic circuits separately adjusted ior actuation in single operating coil linking all oi said magnetic circuits and serving to energize all oi said circuits, and electrical energy storage means connected to discharge into said coil so that the decay oi current in said coil will cause said magnetic circuits to respond aiter predetermined time intervals to render said portions 0! said current limiting device successively inactive.

2. A motor starter comprising in combination, a current limiting device connected in circuit with the motor, a plurality oi pairs oi normally closed contacts for short circuiting portions of said current limiting device, means ior actuating said contacts comprising a plurality oi core 1 structures which are magnetically independent oi each other, a single operating coil linking said core structures and serving to excite magnetic flux in each oi said core structures, a control de-- vice ior energizing said coil and causing said core structures to open said contacts and insert said current limiting device in circuit with said motor, means responsive to said operation oi said control device ior deenergizing said coll, an electrcal energy storage device connected to said coil and arranged to be connected to a source to provide for the storage oi electrical energy therein andto be disconnected from saidscurceinresponse to said operation oi said control device so that it discharges a decaying current through said coil, said core structures being adjusted to close said pairs of contacts at diiierent values oi exciting flux so that said portions 0! said current limiting device are successively short circuited aiter predetermined time intervals.

. 3. A motor starter comprising in combination,

a current limiting resistor connected in the armature circuit oi the motor. a-piurality oi normally closed electromagnetic contactors ior controlling portions oi said resistorythe core struc- 7 tures oi said contactors being separated so that response to dliierent values oi magnetic flux, a

they are magnetically independent oi each other, and each having drop out adjustment means whereby saidcontactors are adJusted to drop out at diiierent values oi flux. a single operating coil linking all oi said core structures, a control deis vice ior exciting said coil to open said contactors and inserting said resistor in the motor circuit, an electrical energy storage device having connections to a source so as to have energy stored therein and having connections to said coil, 10 means responsive to said opening operation of said contactors ior completing the circuit of said motor to a source oi supply and means responsive to said closing operation oi said contactors ior disconnecting said coil and said energy storage device from said source thereby to cause said energy storage device to discharge a decaying current through said coil to provide sequential dropping out of said contactors and short circuiting of said portions oi said resistor.

4. A motor starter comprising in combination, a current limiting resistor connected in the motor armature circuit, a plurality oi electromagnetic contactors having normally closed contacts ior short circuiting portions oi said resistor, 25 the core structure of said contactors being separated so that they are magnetically independent of each other and each having drop out adjustment means whereby said contactors are ad- Justed to drop out at diflerent values oi flux, a single operating coil linking all oi said core structures, a condenser connected to said coil and also having connections to a supply source. a control device for connecting said condenser to a supply source and ior connecting said coil to a supply source to excite said cores and open said contacts to insert said resistor in said armature circuit, ancra control contactor responsive to said opening operation of said resistor controlling contactors ior connecting said motor to a supply 40 source and ior disconnecting said coil and said condenser irom their source of supply so that said condenser discharges a decaying current through said coil to provide for sequential drop out of said oontactors to effect sequential short 4 circuiting of said portions oi said resistor.

5. A motor starter comprising in combination. a current limiting device connected in the armature circuit of the motor, means for rendering portions oi said current limiting device inefiective comprising an electromagnetic switching means having a plurality oi independent magnetic circuits separately adjusted ior actuation in response to diiierent values oi magnetic flux, an operating coil linking all of said magnetic cir- 55 cults, said coil comprising a high resistance portion having a relatively large number of turns and a low resistance portion having a relatively small number oi turns, 'and electrical energy storage means connected to said high resistance portion of said coil to discharge through said high resistance portion oi said coil so that the decay of current in said portion will cause said magnetic circuits to respond aiter predetermined time intervals to render said portions oi said current limiting device inactive. A

6. A motor starter comprising in combination, a current limiting device connected in the armature circuit oi said motor, a plurality oi pairs oi contacts ior short circuiting portions oi said curv rent limiting device, means ior actuating said contacts comprising a plurality oi magnetic core structures :which are magnetically independent oi each other, a single operating coil linking said core structures, said coil comprising a high re- 75,

sistance portion having a relatively large number of turns and a low resistance portion having a relatively small number of turns, a control device and means responsive to an operation of said control device for energizing said low resistance portion to control said contacts to insert said current limiting device in circuit with said motor. and a capacitor connected to said high resistance portion of said coil, means responsive to said operation of said control device for deenergizing said low turn low resistance portion of said coil and causing said capacitor to discharge a decaying current through said high resistance portion of said coil, said core structures being adjusted to close said pairs of contacts at diflerent values of magnetic flux so that said portions of said. current limiting device are successively short circuited after predetermined time intervals.

CERTIFICATE OF CORRECTION;

Patent No. 2,225,278. November 26, 191w.

FRED H. WINTER;

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 511., strike out the comma after "circuit" and insert instead a period; and second column, line 51, for the reference numeral "550" read --55a--; line 52 t after "2,000" insert the word 'turns-- page 5, first column, line '21, for "thereo" read -thereto-; line 58-59, claim 2, for "electrcal" read -electrical--; and second column, line 26, claim LL, for "structure" read --structures-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 114th day of January, A. D. 9

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

Patent No. 2,225,278.

CERTIFICATE OF CORRECTION;

November 26, 1914.0.

FRED H. WINTER;

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2; first column, line 514.,

strike out the comma after "'circuit" and insert instead a period; and second column, line 51, for the reference numeral "550" read --55e.-; line 52 I after 2,000' insert the word '-turns-+; page 5, first column, line '21, "electrcal" read "structure" read be read with this for "thereo" read -thereto; line 58-59, claim 2, for

and second column, line 26, claim 11,, for -structures--; and that the said Letters Patent should correction therein that the same may conform to the rec- --electrical-;

0rd of the case in the Patent Office.

Signed and sealed this 114th day of January, A. D. 9 L

(Seal) Henry Van Arsdale,

Acting Commissioner of Patents. 

